Abstract: A re-examination under the phase contrast microscope of a collection made in a small lake in Xizang, China, which had been previously referred to Glenodinium gymnodinium Penard, has shown that the cell wall is composed of numerous usually hexagonal platelets, and thus the species should be a relatively common member of the genus Woloszynskia, namely W. tenuissima (Lauterborn) Thompson. Tetradinium intermedium Geitler is an immobile species collected from a small pond in Wuhan City, Hubei Province, China. It was attached on filaments of an Oedogonium species. Both genera are newly recorded in China.

Key words: freshwater Dinophyta, Woloszynskia, Tetradinium, new record, China.